<!DOCTYPE html>
<html>
<head>
	<meta charset="UTF-8">
	<title>AJAX Content</title>
	<style type="text/css">
		li input {
              position:absolute;left:0;margin-left:0;opacity:0;z-index:2;cursor:pointer;height:1em;width:1em;top:0;
}
    input + ol {
                display:none;
}
    input + ol > li {
                     height:0;overflow:hidden;margin-left:-14px!important;padding-left:1px;
}
    li label {
              cursor:pointer;display:block;padding-left:17px;background: url('images/tree_icons.png') no-repeat -18px 0px;
}
    input:checked + ol {
                        background: url('images/tree_icons.png') no-repeat 0px 0px;margin:-22px 0 0 -44px;padding:27px 0 0 80px;height:auto;display:block;
}
    input:checked + ol > li {
                             height:auto;
}
	</style>
</head>
<body>
<div>
	<li>
        <label for="subsubfolder1">下级</label>
        <input id="subsubfolder1" type="checkbox" />
        <ol>
           <li class="file"><a>下级</a></li>
            <li>
                <label for="subsubfolder2">下级</label>
                <input id="subsubfolder2" type="checkbox" />
                <ol>
                 	<li class="file"><a>无限级</a></li>
                    <li class="file"><a>无限级</a></li>
                    <li class="file"><a>无限级</a></li>
                    <li class="file"><a>无限级</a></li>
                    <li class="file"><a>无限级</a></li>
                    <li class="file"><a>无限级</a></li>
                </ol>
            </li>
        </ol>
    </li>
    </div>
</body>
</html>